There have been a number of accidents including many fatalities that involve slow moving objects on rural roads that have rated speeds of 45 to 55 miles per hour (mph). Most of these roads are narrow, winding roads with no shoulders and very limited visibility as a result of the terrain.
Initially, it was thought that it was just agricultural equipment, but as it turns out there are many objects that are slow moving that might have frequent stops and starts on rural roads. These objects include: agricultural equipment, a school bus, a delivery truck, a garbage truck, a horse and buggy, a snow plow, a bicycle, a pedestrian (walking/running), deer or other animals, etc. All of these objects either travel at slower than rated speed or spend a high percentage of their time starting and stopping.
Even the best drivers that are paying 100% attention to the road have issues when encountering these objects. If there is a 50 mph difference between two vehicles—the gap is closed at a rate of 73 feet per second (fps). Even if the driver is lucky enough to have an entire football field between objects (300 feet) that gap is covered in just over 4 seconds.
Many new vehicles will soon be designed with warning systems to aid drivers in avoiding some of these collisions. However, even these systems cannot see over hills or around corners.
Previous attempts to reduce the accident rates include slow moving vehicle triangles, tail lights, and road signs that inform travelers, for example, of school bus stops. The slow moving vehicle triangles and the tail lights travel with the vehicle. Therefore, they are not seen until several seconds before impact resulting in insufficient time for a fast moving driver to react. Stationary road signs are always there, but it is very easy to ignore them because nothing makes them interactive.